import { getPublicSuffix } from './getPublicSuffix'

/**
 * Generates the permutation of all possible values that {@link domainMatch} the given `domain` parameter. The
 * array is in shortest-to-longest order. Useful when building custom {@link Store} implementations.
 *
 * @example
 * ```
 * permuteDomain('foo.bar.example.com')
 * // ['example.com', 'bar.example.com', 'foo.bar.example.com']
 * ```
 *
 * @public
 * @param domain - the domain to generate permutations for
 * @param allowSpecialUseDomain - flag to control if {@link https://www.rfc-editor.org/rfc/rfc6761.html | Special Use Domains} such as `localhost` should be allowed
 */
export function permuteDomain(
  domain: string,
  allowSpecialUseDomain?: boolean,
): string[] | undefined {
  const pubSuf = getPublicSuffix(domain, {
    allowSpecialUseDomain: allowSpecialUseDomain,
  })

  if (!pubSuf) {
    return undefined
  }
  if (pubSuf == domain) {
    return [domain]
  }

  // Nuke trailing dot
  if (domain.slice(-1) == '.') {
    domain = domain.slice(0, -1)
  }

  const prefix = domain.slice(0, -(pubSuf.length + 1)) // ".example.com"
  const parts = prefix.split('.').reverse()
  let cur = pubSuf
  const permutations = [cur]
  while (parts.length) {
    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
    const part = parts.shift()!
    cur = `${part}.${cur}`
    permutations.push(cur)
  }
  return permutations
}
